Make x64 to use the RecordWrite stub. This is a step towards getting

src/x64/assembler-x64.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 1356 matching lines @@
   // Use --code-comments to enable.
   void RecordComment(const char* msg, bool force = false);
 
   // Writes a single word of data in the code stream.
   // Used for inline tables, e.g., jump-tables.
   void db(uint8_t data);
   void dd(uint32_t data);
 
   int pc_offset() const { return static_cast<int>(pc_ - buffer_); }
 
+  // Used for patching the code stream while it is being emitted.
+  inline byte get_opcode(int offset) {

[Lasse Reichstein, 2011/06/07 14:02:53]

Rename to get_byte/set_byte. Or read_byte/patch_byte.
There is nothing opcode-specific in this.

[Erik Corry, 2011/06/08 10:38:55]

No, but it makes the call site clearer.

[Lasse Reichstein, 2011/06/08 10:58:46]

I don't see us using get_opcode anywhere. Just remove it.

[Lasse Reichstein, 2011/06/08 10:58:46]

The call site can make its own local functions by any name, which call the
generic method on the assembler.

The generic method is there now, and public, for anyone to use at any time.
For that reason alone, I think it should be less bound to the current use-case.
E.g., I think it should take a zero-based index, not a pc-based index. It's easy
to convert between the two (using pc_offset()).

Or, preferably, replace it with a macro like:
 PatchableNearJump(byte opcode, Label* label) {
   db(opcode);
   emit_near_disp(label);
 }

but there is a visibility issue to work around with that, since MacroAssembler
cant see emit_near_disp. Perhaps make a db_near_disp(Label*) method for that.

[Erik Corry, 2011/06/08 11:27:11]

I now use set_byte_at and pc_offset instead.

[Erik Corry, 2011/06/08 11:27:11]

It was used in an assert

+    ASSERT(offset < 0);
+    ASSERT(pc_ + offset >= buffer_);
+    return pc_[offset];
+  }
+  inline void set_opcode(int offset, byte opcode) {
+    ASSERT(offset < 0);
+    ASSERT(pc_ + offset >= buffer_);
+    pc_[offset] = opcode;
+  }
+
   PositionsRecorder* positions_recorder() { return &positions_recorder_; }
 
   // Check if there is less than kGap bytes available in the buffer.
   // If this is the case, we need to grow the buffer before emitting
   // an instruction or relocation information.
   inline bool buffer_overflow() const {
     return pc_ >= reloc_info_writer.pos() - kGap;
   }
 
   // Get the number of bytes available in the buffer.
@@ skipping 243 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_H_